Newton's first law: Inertia.
I have been on employment insurance in Canada in my early 20's. It's sweet. I was making $350 a week sitting on my ass...why would I go out there and work 40h at Starbucks for about the same amount of money? What do you do when you get a marginal increase in standard of living by spending all day working? Believe me, watching Netflix is way easier. Whatever you reward will increase, it the case of minimal income you reward idleness and tax anyone who is productive.
Also, the difference between what "people say they would do" and "what they would actually do" are radically different stories. It's like asking people what they would do with a million dollar versus what they actually do once they have it.
I was too. I'm not any more, because having some more than the bare minimum is nicer. Same goes for everyone else, and it doesn't matter if you get that bare minimum with or without constant nagging by authorities.
Unconditional basic income means that everyone gets the same base, everything you want above that requires you to work. The actual problem that you get the same for doing nothing as for working at Starbucks would effectively be solved, the workers would always have some more than those who stay at home.
There you go! That is why I have for the last 30 years refused to take any job where I had to pay into unemployment insurance. The system is corrupt and skews the economic playing field by subsidizing unprofitable industries at the expense of profitable ones.